In general, a balloon catheter applicable for medical uses includes a catheter tube having a lumen extending in the longitudinal direction between opposite ends thereof, a balloon connected to one end of the catheter tube, and a connector connected to the other end of the catheter tube. A fluid injector, such as a syringe, is connected to the connector. The balloon catheter like this is configured such that fluid (possibly liquid) injected into the lumen of the catheter tube from the fluid injector is delivered through the lumen and the balloon is inflated by fluid that has passed through the lumen.
The balloon catheter is inserted into an inner portion (bone, an internal organ, a blood vessel, or the like) of the body from the skin of a subject through a previously-formed surgical passage, with the balloon being contracted (in its original shape). When the balloon catheter is inserted into the portion to be operated on, the balloon is inflated by fluid supplied from the fluid injector to expand the corresponding tissues or restore damaged tissues in the body to an original state.
An amount by which the balloon is inflated and the inflated shape of the balloon is mainly determined by the pressure of fluid applied to the balloon. Thus, when the pressure of fluid applied to the balloon is inaccurately controlled such that an excessive amount of pressure is applied to the balloon, the balloon may be inflated beyond a required level, thereby being deformed to an abnormal shape different from a required shape. For example, the abnormal shape of the balloon may be a shape where one portion is more inflated than the other portions. A variety of abnormal shapes may be caused by coupling relationships with the catheter tube. An abnormally-inflated shape balloon may lead to treatment difficulty and may significantly lower the accuracy of the surgical treatment.
After the balloon catheter is inserted into the body through the surgical passage, when the balloon catheter cannot reach the intended position, the inserted balloon catheter must be removed from the portion to be operated and the surgical passage must be extended. Thereafter, the balloon catheter is reinserted into the body. However, this process is very complicated and is disadvantageous in terms of the speed of the surgical treatment, the improvement of which is required.
In addition, the lumen of the catheter tube includes an inflating lumen, through which fluid from the fluid injector is delivered, and a guide wire lumen, through which a guide wire reinforcing the strength of the catheter tube is inserted. Since the inflating lumen and the guide wire lumen are separately provided on the catheter tube in this manner, it is difficult to fabricate the balloon catheter. In addition, the balloon catheter has a complicated structure, and the outer diameter of the catheter tube has to be increased.